Comment 49 for bug 1546328

@Dmitry, @Ross: I do remember qjackctl from before only allowing singltons :) one could close qjackctl to the systray and start it again from the menu with the result of two qjackctls. That while annoying, is not a real problem provided the user is using jackdbus as it is ok to have more than one application controlling jackdbus. There may be issues if dbus is turned off as jackd then becomes a child process of the qjackctl instance that started it. Another qjackctl can not stop it and quitting the excess qjackctl that does happen to have jackd as child of course stops jackd. This could be confusing, but unless jack is currently in use (recording?) not life shattering. Trying to close the qjackctl with the jackd child will create an exit/cancel dialog to warn the user jack will be stopped. The second qjackctl can still make connections of jack clients.

With the qt4 version, starting qjackctl from the menu will make the already running instance visible rather than start a new one.